package org.jivesoftware.spark.util;

import java.io.BufferedReader;
import java.io.File;
import java.io.IOException;
import java.io.InputStreamReader;
import java.lang.reflect.Constructor;
import java.lang.reflect.Field;
import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;

/**
 * BrowserLauncher is a class that provides one static method, openURL, which opens the default
 * web browser for the current user of the system to the given URL.  It may support other
 * protocols depending on the system -- mailto, ftp, etc. -- but that has not been rigorously
 * tested and is not guaranteed to work.
 * <p/>
 * Yes, this is platform-specific code, and yes, it may rely on classes on certain platforms
 * that are not part of the standard JDK.  What we're trying to do, though, is to take something
 * that's frequently desirable but inherently platform-specific -- opening a default browser --
 * and allow programmers (you, for example) to do so without worrying about dropping into native
 * code or doing anything else similarly evil.
 * <p/>
 * Anyway, this code is completely in Java and will run on all JDK 1.1-compliant systems without
 * modification or a need for additional libraries.  All classes that are required on certain
 * platforms to allow this to run are dynamically loaded at runtime via reflection and, if not
 * found, will not cause this to do anything other than returning an error when opening the
 * browser.
 * <p/>
 * There are certain system requirements for this class, as it's running through Runtime.exec(),
 * which is Java's way of making a native system call.  Currently, this requires that a Macintosh
 * have a Finder which supports the GURL event, which is true for Mac OS 8.0 and 8.1 systems that
 * have the Internet Scripting AppleScript dictionary installed in the Scripting Additions folder
 * in the Extensions folder (which is installed by default as far as I know under Mac OS 8.0 and
 * 8.1), and for all Mac OS 8.5 and later systems.  On Windows, it only runs under Win32 systems
 * (Windows 95, 98, and NT 4.0, as well as later versions of all) that include the
 * FileProtocolHandler method in url.dll, which has been the case for all systems that I have
 * tested.  On other systems, this drops back from the inherently platform-sensitive concept of
 * a default browser and simply attempts to launch Netscape via a shell command.
 * <p/>
 * This code is Copyright 1999 by Eric Albert (ejalbert@cs.stanford.edu) and may be redistributed
 * or modified in any form without restrictions as long as the portion of this comment from this
 * paragraph through the end of the comment is not removed.  The author requests that he be
 * notified of any application, applet, or other binary that makes use of this code, but that's
 * more out of curiosity than anything and is not required.  This software includes no warranty.
 * <p/>
 * Credits:
 * <br>Steven Spencer, JavaWorld magazine (<a href="http://www.javaworld.com/javaworld/javatips/jw-javatip66.html">Java Tip 66</a>)
 * <br>Ron B. Yeh, ZeroG
 * <br>Ben Engber, The New York Times
 *
 * @author Eric Albert (<a href="mailto:ejalbert@cs.stanford.edu">ejalbert@cs.stanford.edu</a>)
 * @author loki der quaeler (modified for osX before adding to weltschmerz frameworks)
 * @version 1.1 (Released July 3, 1999)
 */
public class BrowserLauncher {

    static protected final String OS_X_URL_FILE_NAME = "/tmp/bla_wdml.url";

    /**
     * The Java virtual machine that we are running on.  Actually, in most cases we only care
     * about the operating system, but some operating systems require us to switch on the VM.
     */
    private static int jvm;

    /**
     * The browser for the system
     */
    private static Object browser;

    /**
     * Caches whether any classes, methods, and fields that are not part of the JDK and need to
     * be dynamically loaded at runtime loaded successfully.
     * <p/>
     * Note that if this is <code>false</code>, <code>openURL()</code> will always return an
     * IOException.
     */
    private static boolean loadedWithoutErrors;

    /**
     * The <init>(int) method of com.apple.MacOS.AETarget
     */
    private static Constructor aeTargetConstructor;

    /**
     * The <init>(int, int, int) method of com.apple.MacOS.AppleEvent
     */
    private static Constructor appleEventConstructor;

    /**
     * The <init>(String) method of com.apple.MacOS.AEDesc
     */
    private static Constructor aeDescConstructor;

    /**
     * The findFolder method of com.apple.mrj.MRJFileUtils
     */
    private static Method findFolder;

    /**
     * The getFileType method of com.apple.mrj.MRJOSType
     */
    private static Method getFileType;

    /**
     * The makeOSType method of com.apple.MacOS.OSUtils
     */
    private static Method makeOSType;

    /**
     * The putParameter method of com.apple.MacOS.AppleEvent
     */
    private static Method putParameter;

    /**
     * The sendNoReply method of com.apple.MacOS.AppleEvent
     */
    private static Method sendNoReply;

    /**
     * Actually an MRJOSType pointing to the System Folder on a Macintosh
     */
    private static Object kSystemFolderType;

    /**
     * The keyDirectObject AppleEvent parameter type
     */
    private static Integer keyDirectObject;

    /**
     * The kAutoGenerateReturnID AppleEvent code
     */
    private static Integer kAutoGenerateReturnID;

    /**
     * The kAnyTransactionID AppleEvent code
     */
    private static Integer kAnyTransactionID;

    /**
     * JVM constant for MRJ 2.0
     */
    private static final int MRJ_2_0 = 0;

    /**
     * JVM constant for MRJ 2.1 or later
     */
    private static final int MRJ_2_1 = 1;

    /**
     * JVM constant for any Win32 JVM
     */
    private static final int WINDOWS = 2;

    /**
     * even though OS X is a unix variant, would like to differentiate
     */
    static private final int OS_X = 3;

    /**
     * JVM 
     */
    static private final int LINUX = 4;
    
    /**
     * JVM constant for any other platform
     */
    private static final int OTHER = -1;

    /**
     * The file type of the Finder on a Macintosh.  Hardcoding "Finder" would keep non-U.S. English
     * systems from working properly.
     */
    private static final String FINDER_TYPE = "FNDR";

    /**
     * The creator code of the Finder on a Macintosh, which is needed to send AppleEvents to the
     * application.
     */
    private static final String FINDER_CREATOR = "MACS";

    /**
     * The name for the AppleEvent type corresponding to a GetURL event.
     */
    private static final String GURL_EVENT = "GURL";

    /**
     * The first parameter that needs to be passed into Runtime.exec() to open the default web
     * browser on Windows.
     */
    private static final String WINDOWS_PARAMETER = "url.dll,FileProtocolHandler";

    /**
     * The shell parameters for Netscape that opens a given URL in an already-open copy of Netscape
     * on many command-line systems.
     */
    private static final String NETSCAPE_OPEN_PARAMETER_START = " -remote openURL(";
    private static final String NETSCAPE_OPEN_PARAMETER_END = ")";

    /**
     * The message from any exception thrown throughout the initialization process.
     */
    private static String errorMessage;

    /**
     * An initialization block that determines the operating system and loads the necessary
     * runtime data.
     */
    static {
        loadedWithoutErrors = true;
        String osName = System.getProperty("os.name");
        if ("Mac OS".equals(osName)) {
            String mrjVersion = System.getProperty("mrj.version");
            String majorMRJVersion = mrjVersion.substring(0, 3);
            try {
                double version = Double.valueOf(majorMRJVersion).intValue();
                if (version == 2) {
                    jvm = MRJ_2_0;
                }
                else if (version >= 2.1) {
                    // For the time being, assume that all post-2.0 versions of MRJ work the same
                    jvm = MRJ_2_1;
                }
                else {
                    loadedWithoutErrors = false;
                    errorMessage = "Unsupported MRJ version: " + version;
                }
            }
            catch (NumberFormatException nfe) {
                loadedWithoutErrors = false;
                errorMessage = "Invalid MRJ version: " + mrjVersion;
            }
        }
        else if (osName.startsWith("Windows")) {
            jvm = WINDOWS;
        }
        else if (osName.startsWith("Mac OS X")) {
            jvm = OS_X;
        }
        else if (osName.startsWith("Linux")) {
            jvm = LINUX;
        } else {
            jvm = OTHER;
        }

        if (loadedWithoutErrors) {    // if we haven't hit any errors yet
            loadedWithoutErrors = loadClasses();
        }
    }

    /**
     * This class should be never be instantiated; this just ensures so.
     */
    private BrowserLauncher() {
    }

    /**
     * Called by a static initializer to load any classes, fields, and methods required at runtime
     * to locate the user's web browser.
     *
     * @return <code>true</code> if all intialization succeeded
     *         <code>false</code> if any portion of the initialization failed
     */
    private static boolean loadClasses() {
        switch (jvm) {
            case MRJ_2_0:
                try {
                    Class aeTargetClass = Class.forName("com.apple.MacOS.AETarget");
                    Class osUtilsClass = Class.forName("com.apple.MacOS.OSUtils");
                    Class appleEventClass = Class.forName("com.apple.MacOS.AppleEvent");
                    Class aeClass = Class.forName("com.apple.MacOS.ae");
                    Class aeDescClass = Class.forName("com.apple.MacOS.AEDesc");

                    aeTargetConstructor = aeTargetClass.getDeclaredConstructor(int.class);
                    appleEventConstructor = appleEventClass.getDeclaredConstructor(int.class, int.class, aeTargetClass, int.class, int.class);
                    aeDescConstructor = aeDescClass.getDeclaredConstructor(String.class);

                    makeOSType = osUtilsClass.getDeclaredMethod("makeOSType", String.class);
                    putParameter = appleEventClass.getDeclaredMethod("putParameter", int.class, aeDescClass);
                    sendNoReply = appleEventClass.getDeclaredMethod("sendNoReply");

                    Field keyDirectObjectField = aeClass.getDeclaredField("keyDirectObject");
                    keyDirectObject = (Integer)keyDirectObjectField.get(null);
                    Field autoGenerateReturnIDField = appleEventClass.getDeclaredField("kAutoGenerateReturnID");
                    kAutoGenerateReturnID = (Integer)autoGenerateReturnIDField.get(null);
                    Field anyTransactionIDField = appleEventClass.getDeclaredField("kAnyTransactionID");
                    kAnyTransactionID = (Integer)anyTransactionIDField.get(null);
                }
                catch (ClassNotFoundException cnfe) {
                    errorMessage = cnfe.getMessage();
                    return false;
                }
                catch (NoSuchMethodException nsme) {
                    errorMessage = nsme.getMessage();
                    return false;
                }
                catch (NoSuchFieldException nsfe) {
                    errorMessage = nsfe.getMessage();
                    return false;
                }
                catch (IllegalAccessException iae) {
                    errorMessage = iae.getMessage();
                    return false;
                }
                break;
            case MRJ_2_1:
                try {
                    Class mrjFileUtilsClass = Class.forName("com.apple.mrj.MRJFileUtils");
                    Class mrjOSTypeClass = Class.forName("com.apple.mrj.MRJOSType");
                    Field systemFolderField = mrjFileUtilsClass.getDeclaredField("kSystemFolderType");
                    kSystemFolderType = systemFolderField.get(null);
                    findFolder = mrjFileUtilsClass.getDeclaredMethod("findFolder", mrjOSTypeClass);
                    getFileType = mrjFileUtilsClass.getDeclaredMethod("getFileType", File.class);
                }
                catch (ClassNotFoundException cnfe) {
                    errorMessage = cnfe.getMessage();
                    return false;
                }
                catch (NoSuchFieldException nsfe) {
                    errorMessage = nsfe.getMessage();
                    return false;
                }
                catch (NoSuchMethodException nsme) {
                    errorMessage = nsme.getMessage();
                    return false;
                }
                catch (SecurityException se) {
                    errorMessage = se.getMessage();
                    return false;
                }
                catch (IllegalAccessException iae) {
                    errorMessage = iae.getMessage();
                    return false;
                }
                break;
        }
        return true;
    }

    /**
     * Attempts to locate the default web browser on the local system.  Caches results so it
     * only locates the browser once for each use of this class per JVM instance.
     *
     * @return The browser for the system.  Note that this may not be what you would consider
     *         to be a standard web browser; instead, it's the application that gets called to
     *         open the default web browser.  In some cases, this will be a non-String object
     *         that provides the means of calling the default browser.
     */
    private static Object locateBrowser() {
        if (browser != null) {
            return browser;
        }
        switch (jvm) {
            case MRJ_2_0:
                try {
                    Integer finderCreatorCode = (Integer)makeOSType.invoke(null, FINDER_CREATOR);
                    Object aeTarget = aeTargetConstructor.newInstance(finderCreatorCode);
                    Integer gurlType = (Integer)makeOSType.invoke(null, GURL_EVENT);
                    // Don't set browser = appleEvent because then the next time we call
                    // locateBrowser(), we'll get the same AppleEvent, to which we'll already have
                    // added the relevant parameter. Instead, regenerate the AppleEvent every time.
                    // There's probably a way to do this better; if any has any ideas, please let
                    // me know.
                    return appleEventConstructor.newInstance(gurlType, gurlType, aeTarget, kAutoGenerateReturnID, kAnyTransactionID);
                }
                catch (IllegalAccessException iae) {
                    browser = null;
                    errorMessage = iae.getMessage();
                    return browser;
                }
                catch (InstantiationException ie) {
                    browser = null;
                    errorMessage = ie.getMessage();
                    return browser;
                }
                catch (InvocationTargetException ite) {
                    browser = null;
                    errorMessage = ite.getMessage();
                    return browser;
                }
            case MRJ_2_1:
                File systemFolder;
                try {
                    systemFolder = (File)findFolder.invoke(null, kSystemFolderType);
                }
                catch (IllegalArgumentException iare) {
                    browser = null;
                    errorMessage = iare.getMessage();
                    return browser;
                }
                catch (IllegalAccessException iae) {
                    browser = null;
                    errorMessage = iae.getMessage();
                    return browser;
                }
                catch (InvocationTargetException ite) {
                    browser = null;
                    errorMessage = ite.getTargetException().getClass() + ": " + ite.getTargetException().getMessage();
                    return browser;
                }
                String[] systemFolderFiles = systemFolder.list();
                // Avoid a FilenameFilter because that can't be stopped mid-list
                for (String systemFolderFile : systemFolderFiles) {
                    try {
                        File file = new File(systemFolder, systemFolderFile);
                        if (!file.isFile()) {
                            continue;
                        }
                        Object fileType = getFileType.invoke(null, file);
                        if (FINDER_TYPE.equals(fileType.toString())) {
                            browser = file.toString();    // Actually the Finder, but that's OK
                            return browser;
                        }
                    }
                    catch (IllegalArgumentException iare) {
                        errorMessage = iare.getMessage();
                        return null;
                    }
                    catch (IllegalAccessException iae) {
                        browser = null;
                        errorMessage = iae.getMessage();
                        return browser;
                    }
                    catch (InvocationTargetException ite) {
                        browser = null;
                        errorMessage = ite.getTargetException().getClass() + ": " + ite.getTargetException().getMessage();
                        return browser;
                    }
                }
                browser = null;
                break;
            case WINDOWS:
                browser = "rundll32.exe";
                break;
            case LINUX:
            	try {
            		browser = executeWhich("firefox");
                	if (browser == null)
                		browser = executeWhich("mozilla");
                	if (browser == null)
                		browser = executeWhich("opera");
                	if (browser == null)
                		browser = executeWhich("konqueror");
            	}
				catch (Exception e) { 
					// if no which is installed then use firefox
					browser = "firefox";
				}
                break;                                
            case OTHER:
            default:
                browser = "netscape";
                break;
        }
        return browser;
    }
        
    private static String executeWhich(String binaryName) throws IOException {
        Process which = Runtime.getRuntime().exec(new String[] {"which", binaryName});
        BufferedReader reader = new BufferedReader(new InputStreamReader(which.getInputStream()));
        String result = reader.readLine();
        reader.close();

        return result;
    }

    /**
     * Attempts to open the default web browser to the given URL.
     *
     * @param url The URL to open
     * @throws IOException If the web browser could not be located or does not run
     */
    public static void openURL(String url) throws IOException {
        if (!loadedWithoutErrors) {
            throw new IOException("Exception in finding browser: " + errorMessage);
        }
        Object browser = locateBrowser();
//        System.out.println(browser);
        if (browser == null) {
            throw new IOException("Unable to locate browser: " + errorMessage);
        }
        switch (jvm) {
            case MRJ_2_0:
                Object aeDesc;
                try {
                    aeDesc = aeDescConstructor.newInstance(url);
                    putParameter.invoke(browser, keyDirectObject, aeDesc);
                    sendNoReply.invoke(browser);
                }
                catch (InvocationTargetException ite) {
                    throw new IOException("InvocationTargetException while creating AEDesc: " + ite.getMessage());
                }
                catch (IllegalAccessException iae) {
                    throw new IOException("IllegalAccessException while building AppleEvent: " + iae.getMessage());
                }
                catch (InstantiationException ie) {
                    throw new IOException("InstantiationException while creating AEDesc: " + ie.getMessage());
                }
                break;
            case MRJ_2_1:
                Runtime.getRuntime().exec(new String[]{(String)browser, url});
                break;
            case WINDOWS:
                Runtime.getRuntime().exec(new String[]{(String)browser, WINDOWS_PARAMETER, url});
                break;
            case OS_X:
                BrowserLauncher.launchForOSX(url);
                break;
            case OTHER:
                // Assume that we're on Unix and that Netscape is installed

                // First, attempt to open the URL in a currently running session of Netscape
                Process process = Runtime.getRuntime().exec(browser +
                        NETSCAPE_OPEN_PARAMETER_START + url +
                        NETSCAPE_OPEN_PARAMETER_END);
                try {
                    int exitCode = process.waitFor();
                    if (exitCode != 0) {    // if Netscape was not open
                        Runtime.getRuntime().exec(new String[]{(String)browser, url});
                    }
                }
                catch (InterruptedException ie) {
                    throw new IOException("InterruptedException while launching browser: " + ie.getMessage());
                }
                break;
            default:
                // This should never occur, but if it does, we'll try the simplest thing possible
                Runtime.getRuntime().exec(new String[]{(String)browser, url});
                break;
        }
    }

    /**
     * THERE HAS GOT TO BE A BETTER WAY TO DO THIS -- email out to mailing
     * lists; waiting for reply.
     *
     * @param url URL to launch.
     * @throws IOException if there was an error while launching.
     */
    static protected void launchForOSX(String url)
            throws IOException {
        String run = "open " + url;
        Process process = Runtime.getRuntime().exec(run);

        try {
            int exitCode = process.waitFor();

            if (exitCode != 0) { // failed :-(
                System.out.println("browser launch failed - exit code: "
                        + exitCode);
            }
        }
        catch (InterruptedException ie) {
            throw new IOException("Exception while launching browser: "
                    + ie.getMessage());
        }
    }

}
